Upload file with Rails

[faust 1111]

i try upload file
i use Rails 3 and CouchRest
like this

@video = Video.new(params[:video])

   if @video.save
     @video.put_attachment('source', params[:video][:source])
   end

and have error

redundant UTF-8 sequence

backtrace
http://gist.github.com/356934

Can any one help?
any examples uploading files?